Other things related to rsk data: [[,rsk-method,
[[<-,rsk-method, as.rsk,
plot,rsk-method, read.rsk,
rsk-class, rskPatm,
rskToc, rsk,
summary,rsk-method
Other functions that subset oce objects: subset,adp-method,
subset,adv-method,
subset,amsr-method,
subset,argo-method,
subset,cm-method,
subset,coastline-method,
subset,ctd-method,
subset,echosounder-method,
subset,lobo-method,
subset,met-method,
subset,oce-method,
subset,odf-method,
subset,sealevel-method,
subset,section-method,
subset,topo-method